Cellular materials can be made to combine high strength to weight ratio, elastic resilience and energy absorbing properties. They are attractive for lightweight structures, packaging and insulating purposes. Nature provides an abundance of examples in wood, leaves, cork, bone and many other organically built structures that display a wealth of intricate and ingenious shapes, forms and designs. Bone and its growth response to stresses is an example of the versatility and of the adaptability of cell structures to mechanical requirements.
Manmade cellular materials have found many applications because it is possible to tailor the properties for a variety of purposes, such as for packaging, insulating, or structural purposes. Open cell structures such as foamed polymers constitute perhaps the most widely used manmade cell materials. Significant developments have also been made in the fabrication of cell materials from metals, glass, ceramics and graphite. Honeycomb structures may be considered as cell structures with designed architecture. They find use in structural applications such as for lightweight aircraft components.
A variety of methods exist for producing cell structures of less well defined design. Such are the foaming methods. Metallic foams are well suited for a variety of applications including impact energy absorbers, silencers, filters, heaters, heat exchangers and structural parts, but more cost effective competitive materials are generally used. Open metal foams were investigated by Ford Motor Company in the early 1970's, but they have not yet found significant use in motor vehicles. One reason for this may be that such foams can be easily crushed in compression due to buckling and plastic collapse of relatively thin cell walls.
Closed cell metal composites offer advantages over open cell metal foams. An object of this invention is to provide an artificial closed cell metal composite having desirable strength as well as damping or elastic properties. Depending upon the materials used in forming the closed cell metal composites, the resulting bodies can be compatibly adapted for use in a variety of applications ranging from biomedical prostheses to automotive brake disks, various castings and to structural parts.